Engine Rebuild Update

Our Mechanic at A&M, Michael, is up to his armpits in our engines! The transmission is off the port engine and was delivered to the transmission shop on Monday—no word as of yet on its prognosis. We are hoping to hear something early next week.

The Port engine has been stripped down and is in the process of re-assembly. In general, there haven’t been any major surprises. The cylinder sleeves showed a lot of pitting and rust which we had seen when the mechanic bore-scoped the cylinders. Given how much we run the engine, it’s surprising. The crankshaft and connecting rod bearings also showed quite a bit of wear.

The prior owner of the boat had the dashboard replaced, and we’ve always suspected that the Hobbs meter that counts hours on the engine may have been replaced when the dash was done. Given the wear, my mechanic seems to think there may be a couple hundred more hours on the engines than the meter shows.

In November of last year, when we had the first round of work done on the boat, we replaced all 12 of the fuel injectors with new ones from Yanmar. Michael tested them and found that 6 of the 12 were bad. A 50% failure rate on a $600 part! We’re going to go back to Yanmar and see about warranty coverage. He is also going to test the replacements before installing them. We’ve replaced them before with no issues, which is why we usually choose to go with Yanmar Brand parts rather than re-builts or after-market parts.

Another item of interest was the amount of sludge in the bottom of the oil pan. I religiously change my oil every 150 hours, letting the engines warm up, then using a suction pump to draw the oil out. Many boats don’t have a drain plug in the oil pan like a car because they sit between the stringers (boat frame), and using a pump is a pretty common practice. The downside to the pump method is that you can never get all of the oil out. There’s still a quart or two in the bottom of the pan that sits there, and since this is the heaviest/dirtiest oil, it builds up over time.

While the engines and oil pan are out, the mechanic is installing an oil drain plug for me so that we can get all of the oil out when we do an oil change.

The Port engine should be finished this week, except for the injectors and doing the final install of the oil pan. The Starboard engine is next week’s project!

Along with 100 other minor parts (nuts, bolts, gaskets, pins, O rings), the major components we are replacing are:

Pistons
Piston rings
Cylinder liners
Connecting rods
Connecting rod bearings
Cranks shaft bearings (we were going to replace the crankshafts, but they are $22,000 EACH!)
Oil pump
Valves
Cylinder heads
Starters
Fresh water pump

A special thanks to Michael from A&M for sharing photos. A&M always sends a daily text message with the number of hours worked, a description of what was done, and photos of the work. This is not typical of marine mechanics (or any mechanic, for that matter)! Michael has taken some extra photos and videos of the work. Below is a gallery of images from the rebuild.

(click on images to enlarge)